Yarn tension sensors on textile machines have been known for a long time and serve to ascertain yarn breaks, or directly to control the yarn tension by means of a yarn tensioning device, with the goal being to make this tension uniform.
Such devices are known, for instance from DE-OS 20 60 733 or SU-UHF 12 17 764. In these known devices, the deflection of a yarn guide, which is dependent on the yarn tension, is transmitted mechanically and converted into control signals to vary the mutual pressing force of tension device plates of a yarn tensioning device. These devices have a relatively high control inertia, which is due to the length of the motion of the yarn guide connected to the yarn tension meter. At high yarn speeds, such devices begin to vibrate, which greatly limits the accuracy of measurement.
The earlier German Patent Application P 40 30 892.8 (which however does not have a publication date prior to the priority date of the present invention) discloses a yarn tension measuring instrument the basic principle of which is based on the measurement of the temperature generated by the sliding friction of the yarn against a yarn guide. This yarn guide, having a temperature sensor, can be disposed in stationary fashion, so that no vibration occurs even at high yarn speeds.
The known yarn tension sensors are not capable of detecting high-frequency yarn tension fluctuations.